Device for cooling an electric wire insulated by extrusion

ABSTRACT

A device for cooling an electric wire during coating of the wire with an extruded plastic insulation. The wire is subjected to jets of cooling water which are directed substantially in the advancing direction of the wire.

United States Patent [191 Riekkinin [451 July 17,1973

1 1 DEVICE FOR COOLING AN ELECTRIC WIRE INSULATED BY EXTRUSION [75] Inventor: Asko S. Riekkinen, Kirkkonummi,

Finland [73] Assignee: OY Nokia AB,Helsinki,Finland W [22] Filed: July 13, 1970 21 Appl. No.: 54,128

[52] US. Cl. 134/122, 134/199 937,551 10/1909 Remmen 134/122 X 1,211,277 1/1917 Bloom 134/122 1,885,080 10/1932 Cherry et a1...... 134/122 UX 2,536,208 1/1951 Nystrom l 134/15 2,542,237 2/1951 Dewey 134/122 2,565,855 8/1951 Jordan v 134/64 2,586,800 2/1952 Elvin et al 134/15 X 2,616,437 11/1952 Secor v v v 134/122 3,445,285 5/1969 Nast ct al 134/15 X Primary Examiner-Robert L. Bleutge Att0rney--Waters, Roditi, Schwartz & Nissen [57] ABSTRACT A device for cooling an electric wire during coating of the wire with an extruded plastic insulation. The wire is subjected to jets of cooling water which are directed substantially in the advancing direction of the wire.

1 Claim, 5 Drawing Figures PATENIE JUL] 7 ms SHEET 2 DEVICE FOR COOLING AN ELECTRIC WIRE INSULATED BY EXTRUSION The invention concerns apparatus for cooling an electric wire while it is being coated with an extruded plastic insulation coating by directing jets of cooling water upon the wire.

The coating of a wire generally takes place as follows. The metal wire runs by way of drawing wheels to an extruder, from which the required plastic is pressed while hot onto the wire. Before the wire is wound onto a spool it also has to be cooled, with which purpose the present invention is associated. Cooling has previously been carried out by means of a water trough above which there are water taps at mutual intervals, from which water is directed perpendicularly onto the wire in the trough. As the water does not have a velocity component in the direction of the wire, it causes friction and water drops tend to travel with the wire and drift to one end of the trough. The arising friction becomes quite great when the extrusion speed rises above 1,000 meters per minute, and this necessitates a long cooling trough. It has been found that the friction causes a slight stretching of the wire, which in turn involves a change especially in its electrical but also in its mechanical characteristics, particularly in the case of thin telephone conductors composed of such wires. If the friction causes irregular stretching of the wires, this will result in a non-homogenity of a cable composed of several wires and possibly a fairly big change in characteristics.

The purpose of the invention is to eliminate the risk of stretching the wire and the loss of energy caused by friction at great extrusion speeds.

The purpose referred to is achieved by means of the method according to the invention, which is characterized by the fact that the jets of water are essentially directed to run parallel with the direction of motion of the wire.

The following advantagesare attained by means of the invention. As the water is sprayed in the direction of the wire and at least with substantially the same speed as the wire, the disadvantages caused by friction between wire and water are eliminated. There will moreover be water along the whole length of the cooling distance of the wire, and the cooling surface of the water will thus be greater, i.e. cooling will be intensified and this will allow for a shortening of the cooling distance. Spool-winding can similarly be speeded up. The result of this is increased production.

To save floor space, the wire can be guided to run along two troughs, one above the other, i.e. first through the upper trough, over a wheel at the end of which it will be brought back in the opposite direction along the lower trough, and then over a wheel at the end of this latter trough back to the upper trough; two channels thus being necessary in the upper trough. From here it will be passed to be wound onto spools.

As during cooling, the wire may occasionally drag locally against the bottom or some other part of the v trough, especially when the cooling troughs are long ones, which will cause sliding friction, itmay be advantageous to keep the speed of the jets higher than the motion speed of the wire. A power component promoting the advancing motion of the wire willthus be'obtained compensating the extra sliding friction.

The invention is described more closely below, with reference to the encloseddrawings, in which FIG. 1 shows diagrammatically the principle of a wire cooling device,

FIG. 2 shows on a larger scale, in, vertical crosssection, a spraying head used in the device for the upper trough,

FIG. 3 shows the same for the lower trough,

FIG. 4 shows a section along line IVIV in FIG. 3, and

FIG. 5 shows a section along line VV in FIG. 3.

In FIG. 1 a metal wire 1 being coated isled to an extruder 2 where it is coated with an insulating plastic mantle. The coated wire 3 runs further to a cooling device 4 over a guiding wheel 5 to an upper trough 6 and further over a guiding wheel 7 to a lower trough 8 and thereafter over the guiding wheel 5 back to the upper trough 6 and finally out of the device to a winding machine 9.

In the upper and lower troughs of the cooling device, spray heads 10 and 11 have been fitted at intervals for the cooling water which, in FIG. 1 are shown only in the form of vertical lines.

The spraying head 11 in FIG. 3 comprises a frame 12 which is fixed by bolts to the cooling trough 8, which is U-shaped in cross-section and is closed by a lid 13. A hole 14 extends through the frame and joins an upper groove 15 for the insertion of the wire 3 that is to be cooled. The hole is surrounded by a water-space 16 which is connected through an aperture 17 to a cooling-water inlet channel 18 in the trough 8. At the opposite ends of the frame, endplates 19, 20 have been bolted bearing cavities corresponding to the hole 14 and the groove 15. In the endplate 20 on the outlet side a number of holes 21 functioning as spraying nozzles have been formed at regular intervals around the hole 14. The holes have been so made in respect of the wire passing through that the water jets 22 leaving the holes are directed essentially in the advancing direction of the wire converging somewhat as is shown in FIG. 5. The wire-cooling water of the jets is gathered in an outlet gutter 23 of the cooling trough.

The spray head of the upper trough differs essentially from that of the lower trough only in the respect that it has the double amount of holes 14, grooves 15 and spray holes 21.

The upper edge of the trough has grooves in which have been fitted packings 24, and the lid has flanges 25 which prevent water from being sprinkled in between the packings and the lid.

The water pressure and the size of the holes are so selected as to ensure that the speed of the water jets when meeting the wire is at least as high as the velocity of the wire and preferably somewhat higher.

The cooling troughs and the frames of the nozzles are in this application made of extrusion-pressed formed bar parts.

The drawing and the description relating thereto are only intended to elucidate the idea of the invention. In details, the invention may vary considerably within the scope of the patent claims.

I claim:-

1. A device for cooling anelectric wire coated with an extruded plastic insulation coating, comprising a cooling trough for the coated wire to be cooled, said trough being U-shaped in cross section forming an upwardlydirectedlongitudinal open slot covered by a removable lid, and spray heads arranged in the trough at mutual distances at the bottom of said trough, said connected to the water space to direct cooling water jets towards the wire essentially in the direction of movement of the wire through said groove, said water space being connected by an aperture to a cooling water channel in said cooling trough. 

1. A device for cooling an electric wire coated with an extruded plastic insulation coating, comprising a cooling trough for the coated wire to be cooled, said trough being U-shaped in cross section forming an upwardly directed longitudinal open slot covered by a removable lid, and spray heads arranged in the trough at mutual distances at the bottom of said trough, said spray heads comprising a frame forming an upwardly open groove in the longitudinal direction of the trough for through-passage of said wire and a water space around said groove and further comprising end plates closing the water space of the frame at opposite ends of the gRoove, the outlet end plate being provided with holes spaced around the outlet end of said groove and connected to the water space to direct cooling water jets towards the wire essentially in the direction of movement of the wire through said groove, said water space being connected by an aperture to a cooling water channel in said cooling trough. 